linux-kernel - Re: [PATCH 14/29] x86/ibt: Add IBT feature, MSR and #CP handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YhStwI95PmMyxgqx@hirez.programming.kicks-ass.net>
Date:   Tue, 22 Feb 2022 10:32:48 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc:     "Poimboe, Josh" <jpoimboe@...hat.com>,
        "hjl.tools@...il.com" <hjl.tools@...il.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "joao@...rdrivepizza.com" <joao@...rdrivepizza.com>,
        "Cooper, Andrew" <andrew.cooper3@...rix.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "samitolvanen@...gle.com" <samitolvanen@...gle.com>,
        "ndesaulniers@...gle.com" <ndesaulniers@...gle.com>,
        "Milburn, Alyssa" <alyssa.milburn@...el.com>
Subject: Re: [PATCH 14/29] x86/ibt: Add IBT feature, MSR and #CP handling

On Tue, Feb 22, 2022 at 04:38:22AM +0000, Edgecombe, Rick P wrote:
> On Fri, 2022-02-18 at 17:49 +0100, Peter Zijlstra wrote:
> > +       cr4_set_bits(X86_CR4_CET);
> > +
> > +       rdmsrl(MSR_IA32_S_CET, msr);
> > +       if (cpu_feature_enabled(X86_FEATURE_IBT))
> > +               msr |= CET_ENDBR_EN;
> > +       wrmsrl(MSR_IA32_S_CET, msr);
> 
> So I guess implicit in all of this is that MSR_IA32_S_CET will not be
> managed by xsaves (makes sense).
> 
> But it still might be good to add the supervisor cet xfeature number to
> XFEATURE_MASK_SUPERVISOR_UNSUPPORTED, with analogous reasoning to
> XFEATURE_MASK_PT.

Yeah, no, I'm not touching that.